1. Field of the Invention
The present invention relates to a lens barrel which can be used as a photographing lens of an AF camera, and more specifically, to a switching mechanism of such a lens barrel for switching between automatic focusing and manual focusing.
2. Description of the Related Art
FIGS. 8 through 11 show a conventional interchangeable lens barrel having a switching mechanism between an automatic focusing mode and a manual focusing mode. The lens barrel 01 includes a stationary barrel 03 having a small-diameter ring portion 07 and a large-diameter ring portion 05 positioned radially outside the small-diameter ring portion 07. A distance adjustment ring 09 is positioned between the small-diameter ring portion 07 and the large-diameter ring portion 05 to be freely rotatable about an optical axis O. An AF/MF switching ring 011 for switching between an automatic focusing mode and a manual focusing mode is fitted on the large-diameter ring portion 05. The AF/MF switching ring 011 is freely rotatable about the optical axis O and movable along the optical axis O relative to the large-diameter ring portion 05 between an AF position and an MF position to switch between an automatic focusing mode and a manual focusing mode, respectively. A lens holding ring 013 for holding a focusing lens group L is screw-engaged with the small-diameter ring portion 07. A rotation of the distance adjustment ring 09 causes the lens holding ring 013 to move along the optical axis O while rotating about the optical axis O. The lens barrel 01 is provided between the large-diameter ring portion 05 and the small-diameter ring portion 07 with an AF drive mechanism 015 which transfers a rotation of an AF motor (provided in a camera body (not shown) to which the lens barrel 01 is mounted) to the distance adjustment ring 09 to perform an autofocusing operation when the AF/MF switching ring 011 is in the AF position (automatic focusing mode). When the AF/MF switching ring 011 is in the MF position (manual focusing mode), the AF drive mechanism 015 is disengaged from the distance adjustment ring 09.
The large-diameter ring portion 05 is provided, on an outer peripheral surface thereof at the front end of the large-diameter ring portion 05, with a plurality of stop grooves 017 which extend in a direction of the optical axis O (i.e., optical axis direction). The plurality of stop grooves 017 are arranged in a circumferential direction of the large-diameter ring portion 05. An AF engaging member 019 is fixed to an inner peripheral surface of the AF/MF switching ring 011. The AF engaging member 019 is engaged with one of the plurality of stop grooves 017 to prevent the AF/MF switching ring 011 from rotating when the AF/MF switching ring 011 is in the AF position (see FIGS. 8 and 10). The distance adjustment ring 09 is provided at the front end thereof with a plurality of engaging grooves 021 which extend in the optical axis direction (see FIG. 11). The plurality of engaging grooves 021 are arranged in a circumferential direction of the distance adjustment ring 09. The AF/MF switching ring 011 is provided at the front end thereof with an inner flange 023. An MF engaging pin 025 projects rearwards from a rear surface of the inner flange 023 to be engaged with any one of the plurality of engaging grooves 021. The MF engaging pin 025 is engaged in one of the plurality of engaging grooves 021 when the AF/MF switching ring 011 is in the MF position to transmit rotation of the AF/MF switching ring 011 to the distance adjustment ring 09.
In the lens barrel 01 having the above described structure, the MF engaging pin 025 is disengaged from the plurality of engaging grooves 021 when the AF/MF switching ring 011 is in the AF position to allow the AF drive mechanism 015 to perform an auto-focusing operation. When the AF/MF switching ring 011 is in the MF position, the MF engaging pin 025 is engaged in one of the plurality of engaging grooves 021 so that a rotation of the AF/MF switching ring 011 is transferred to the distance adjustment ring 09 to perform a focusing operation (manual focusing operation) when the AF/MF switching ring 011 is manually rotated.
Installation of both the AF engaging member 019 and the MF engaging pin 025 at different positions on the AF/MF switching ring 011 increases the cost of production, the cost of assembly and the size of the lens barrel 01.
The present invention provides a lens barrel having a switching mechanism between an automatic focusing mode and a manual focusing mode, wherein the cost of production and the cost of assembly of the lens barrel can be reduced while further miniaturizing the lens barrel.
According to an aspect of the present invention, a switching mechanism of a lens barrel for switching between an automatic focusing mode and a manual focusing mode, the switching mechanism including a stationary barrel having at least one stop groove; a lens holding ring, positioned concentrically with the stationary barrel, the lens holding ring holding at least one lens group; a distance adjustment ring which is positioned concentrically with the stationary barrel, immovable along an optical axis relative to the stationary barrel, and rotatable about the optical axis relative to the stationary barrel, wherein a rotation of the distance adjustment ring causes the lens holding ring to move along the optical axis, and wherein the distance adjustment ring includes at least one engaging groove; and an AF/MF switching ring which is positioned concentrically with the stationary barrel, movable along the optical axis relative to the stationary barrel, and rotatable about the optical axis relative to the stationary barrel, wherein movement of the AF/MF switching ring relative to the stationary barrel between an AF position and an MF position switches between the automatic focusing mode and the manual focusing mode, respectively, and wherein the AF/MF switching ring includes an engaging member which is selectively engaged with the stop groove and the engaging groove. The AF/MF switching ring is prevented from rotating relative to the stationary barrel by engagement of the engaging member with the stop groove while a driving force is transferred from a power source to the distance adjustment ring to move the lens holding ring along the optical axis when the AF/MF switching ring is in the AF position. A rotation of the AF/MF switching ring is transferred to the distance adjustment ring to move the lens holding ring along the optical axis via engagement of the engaging member with the engaging groove while the driving force is prevented from being transferred from the power source to the distance adjustment ring when the AF/MF switching ring is in the MF position.
It is desirable for the engaging member to include a first engaging portion and a second engaging portion which are fixed at opposite ends of a leaf spring in the optical axis direction to be engageable with the stop groove and the engaging groove, respectively, the leaf spring being elongated in the optical axis direction and a central portion thereof being fixed to said AF/MF switching ring. The leaf spring is resiliently deformed to move the first engaging portion to a non-engaging position thereof, wherein the first engaging portion is disengaged from the stop groove, when the AF/MF switching ring moves from the MF position to the AF position in the case where the first engaging portion is not aligned with the stop groove in the circumferential direction thereof. The leaf spring is resiliently deformed to move the second engaging portion to a non-engaging position thereof wherein the second engaging portion is disengaged from the engaging groove when the AF/MF switching ring moves from the AF position to the MF position in the case where the second engaging portion is not aligned with the engaging groove in the circumferential direction.
In another embodiment, a switching mechanism of a lens barrel for switching between an automatic focusing mode and a manual focusing mode is provided, the switching mechanism including a stationary barrel having at least one stop groove; a lens holding ring holding at least one lens group which functions as a focusing lens, the lens holding ring being movable in an optical axis direction; a distance adjustment ring being relatively rotatable with respect to the stationary barrel so that a rotation of the distance adjustment ring causes the lens holding ring to move along the optical axis, the distance adjustment ring being provided with at least one engaging groove; an AF/MF switching ring being movable between an AF position and an MF position along the optical axis and rotatable relative to the stationary barrel; an AF driving power mechanism which rotates the distance adjustment ring when the AF/MF switching ring is positioned at the AF position in accordance with object distance information; and a first engaging portion and a second engaging portion which are fixed at opposite ends of a leaf spring in the optical axis direction to be engageable with the stop groove and the engaging groove, respectively, the leaf spring being elongated in the optical axis direction and a central portion thereof being fixed to the AF/MF switching ring. The leaf spring is resiliently deformed to move the first engaging portion to a non-engaging position thereof, wherein the first engaging portion is disengaged from the stop groove, when the AF/MF switching ring moves from the MF position to the AF position in the case where the first engaging portion is not aligned with the stop groove in the circumferential direction thereof. The leaf spring is resiliently deformed to move the second engaging portion to a non-engaging position thereof wherein the second engaging portion is disengaged from the engaging groove when the AF/MF switching ring moves from the AF position to the MF position in the case where the second engaging portion is not aligned with the engaging groove in the circumferential direction.
It is desirable for the stop groove of the stationary barrel to include a plurality of stop grooves arranged in a circumferential direction of the stationary barrel.
It is desirable for the engaging groove of the distance adjustment ring to include a plurality of stop grooves arranged in a circumferential direction of the stationary barrel.
It is desirable for the plurality of stop grooves to be arranged at equi-angular intervals.
It is desirable for the plurality of engaging grooves to be arranged at equi-angular intervals.
It is desirable for the AF/MF switching ring to be fitted on the stationary barrel to be manually moved between the AF position and the MF position, and for the AF/MF switching ring to include a recess on an inner peripheral surface thereof, the engaging member being positioned in the recess.
It is desirable for the leaf spring to be resiliently deformed so that the first engaging portion moves radially outwards when the AF/MF switching ring moves from the MF position to the AF position in the case where the first engaging portion is not aligned with the stop groove in the circumferential direction, and for the leaf spring to be resiliently deformed so that the second engaging portion moves radially outwards when the AF/MF switching ring moves from the AF position to the MF position if the second engaging portion is not aligned with the engaging groove in the circumferential direction.
In another embodiment, a switching mechanism of a lens barrel for switching between an automatic focusing mode and a manual focusing mode is provided, the switching mechanism including a stationary ring having a first plurality of engaging grooves arranged at equi-angular intervals about an optical axis; an AF/MF switching ring fitted on the stationary ring to be manually movable along the optical axis relative to the stationary ring between an AF position and an MF position to switch between the automatic focusing mode and the manual focusing mode, respectively; a rotatable ring fitted in the stationary ring to be rotatable about the optical axis without moving along the optical axis relative to the stationary ring, the rotatable ring having a second plurality of engaging grooves arranged at equi-angular intervals about an optical axis; and an engaging member fixed to opposite ends of a leaf spring in the optical axis direction, the leaf spring fixed to the AF/MF switching ring, wherein the engaging member includes a first engaging portion and a second engaging portion of the engaging member are engageable in any one of the first plurality of engaging grooves and any one of the second plurality of engaging grooves, respectively. The first engaging portion of the engaging member is engaged in one of the first plurality of engaging grooves when the AF/MF switching ring moves from the MF position to the AF position in the case where the first engaging portion is aligned with the one first engaging groove in the circumferential direction thereof. The second engaging portion of the engaging member is engaged in one of the second plurality of engaging grooves when the AF/MF switching ring moves from the AF position to the MF position in the case where the second engaging portion is aligned with the one second engaging groove in the circumferential direction thereof. The leaf spring is resiliently deformed so that the first engaging portion moves radially outwards when the AF/MF switching ring moves from the MF position to the AF position in the case where the first engaging portion is not aligned with the one first engaging groove in the circumferential direction, and so that the second engaging portion moves radially outwards when the AF/MF switching ring moves from the AF position to the MF position in the case where the second engaging portion is not aligned with the one second engaging groove in the circumferential direction thereof.
It is desirable for the rotatable ring to be driven to rotate by an AF motor provided in a camera body to which the lens barrel is mounted when the AF/MF switching ring is in the AF position, and a focusing lens group to move along the optical axis by a rotation of the AF/MF switching ring via the rotatable ring when the AF/MF switching ring is in the MF position.
The present disclosure relates to subject matter contained in Japanese Patent Applications No. 2002-302679 (filed on Oct. 17, 2002) which is expressly incorporated herein by reference in its entirety.